In the manufacturing processes of semiconductor devices such as LSIs and super LSIs or liquid crystal display panels, light is applied via a mask (also referred to as exposure master plate or reticle) to print patterns. At this time, if particles are present on the mask, light is absorbed or bent by the particles. For this reason, the pattern is deformed or the edge is rugged, impairing the size, quality, and appearance of the pattern. Therefore, a method is employed for preventing particles from adhering to the mask surface by mounting a pellicle with good light transmittance.
Generally, a pellicle includes a metal pellicle frame and a pellicle membrane stretched across one end surface of the pellicle frame. A mask adhesive layer for securing a pellicle on a mask is arranged on the other end surface of the pellicle frame, and the mask adhesive layer is protected by, for example, a sheet-shape material (separator) which is releasable.
To mount the pellicle on the mask, the releasable sheet-shape material is peeled off and then the exposed mask adhesive layer is pressed against the predetermined position of the mask, to secure the pellicle on the mask. By mounting the pellicle on the mask in this way, an exposure light can be transmitted without the influences of particles or the like.
A pellicle using an acrylic emulsion adhesive as a mask adhesive, is suggested (for example, see Patent Literature 1). Surface protection films for optical usages containing polypropylene elastomers and/or styrene elastomers as a thickening agent layer, are suggested (for example, see Patent Literature 2). Dicing substrate films containing hydrogen additives of styrene-butadiene copolymers (SEBS), polypropylene resins (PP) and olefin thermoplastic elastomers (TPO) as a substrate layer, are suggested (for example, see Patent Literature 3). Resin compositions having a salami-like dispersed structure are suggested, the resin compositions containing the continuous phase of a modified polyphenylene sulfide (PPS) resin and the discontinuous phase of polyester as resin compositions having a phase-separated structure; and the discontinuous phase of the polyester further includes the continuous phase of epoxide-containing polyolefin and the discontinuous phase of other polyolefins (for example, see Patent Literature 4).
Microfabrication of pattern is required for high-integration of semiconductor devices. That is, to achieve high integration of semiconductor devices in a narrow area, it is necessary to minimize semiconductor devices. For this reason, it is necessary to make the width of the pattern and the pitch, which means an interval of the neighboring patterns, smaller. However, microfabrication of the pattern has a limitation due to resolution limitation.
One of the methods for overcoming the resolution limitation in the photolithography process is double patterning. Double patterning is a technique for obtaining two circuit patterns of low density by exposure, and combining these two patterns to obtain a fine pattern of high density (for example, see Patent Literatures 5 and 6). Double patterning is preferably applied to manufacture of semiconductors of the next generation of 22 nm generation (half pitch 32 nm) and subsequent generations.
In double patterning, exposure is performed twice using two masks. For this reason, accuracy of relative positions of the two patterns is important. That is, when the accuracy of the relative positions of a pattern obtained by the first exposure and a pattern obtained by the second exposure is not high, the desired pattern cannot be obtained. Therefore, it is desirable to minimize the deviation of nm level related to relative positions of the two patterns (position deviation of patterns).